(1) Field of the Invention
The present invention relates to a novel triphenyl methane derivative and a method of quantitatively measuring an oxidative substance by using said derivative as a coloring commponent.
(2) Description of the Prior art
Since changes in components of body fluids such as blood, urine and the like are deeply correlated with diseases, measurement of the body fluid components has been important to diagnose the diseases, solve pathological conditions and judge a therapeutic course. For instance, as well known, there have been developed methods of measuring an extremely various kinds of micro-components including cholesterol, triglyceride, glucose, uric acid, monoamine oxidase, bile acid and the like in the blood, and they have been used for the diagnosis of the diseases.
At present, as a method of measuring serum components there is generally popularized a so-called "enzyme method" in which an enzyme reaction is carried out by using an enzyme specifically acting upon an intended component, and a product formed thereby is measured to determine the content of the intended component. With development of oxidizable coloring reagents, there have been increasingly developed and used, for example, a method in which an oxidizable coloring reagent is oxidized with a peroxidase-like substance and an oxidative substance to be led to a coloring system, among them, a method in which an H.sub.2 O.sub.2 generating enzyme, for instance, an oxidase, is applied to generate H.sub.2 O.sub.2 in such an amount as to meet with that, of an intended component, and the generated H.sub.2 O.sub.2 is led to a coloring system with use of a peroxidase and an oxidizable coloring reagent as a coloring component to determine the amount of the intended component through colorimetric determination. That is, there may be recited by way of example a method in which H.sub.2 O.sub.2 generated with a combined use of cholesterol-cholesterol oxidase, glucose-glucose oxidase, triglyceride-lipoprotein lipase-glycerol oxidase, uric acid-uricase, or the like is led to a coloring system by using peroxidase and an oxidizable coloring reagent and a color development is measured by using an photometer to determine the amount of an intended component. As a matter of course, the concentrations of the components in the serum differ depending upon kinds of the components, and therefore the amounts of H.sub.2 O.sub.2 generated through the enzyme reaction varies over a wide range. Accordingly, there have been developed and used oxidizable coloring reagents with sensitivities meeting the intended purposes. For example, an oxidizable coloring reagent combining 4-aminoantipyrine with phenolic compound or N,N-dialkylaniline compound are generally used in the measurement of cholesterol, triglyceride, glucose, uric acid or the like.
Meanwhile, among the body fluid components, there are some components which are contained in the normal serum in an extremely small amount, like monoamine oxidase and bile acid. That is, the monoamine oxidase is an enzyme which acts upon a monoamine compound to generate H.sub.2 O.sub.2 and aldehyde, but the amount of the generated H.sub.2 O.sub.2 is extremely small due to its extremely small concentration in the serum. Thus, the oxidizable coloring reagents of the above combinations are insufficient in sensitivity to quantitatively determine such components. Consequently, an oxidizable coloring reagent with a higher sensitivity is being demanded. Under these circumstances, there has heretofore been developed and used in a commercial base a measuring method using a derivative of leucomethylene blue as the oxidizable coloring reagent with a higher sensitivity. However, this leuco coloring matter has the defect that it is questionable in stability in a solution state, and that a coloring reagent containing this leuco coloring matter is gradually colored during storage.
Further, although for the similar purpose to the above, there have been studied a leucocrystal violet, a leuco malachite green and so on as an oxidizable coloring reagent with high sensitivity which belong to the same triphenyl methane type leuco coloring matters as in the present invention, all of them are difficult to dissolve into water in around the neutral range. Therefore, it is difficult to dissolve them in a desired concentration. Thus, they are insuitable for the measurement of a micro-component.
As a leuco coloring matter improved in this defect, there is proposed bis(4-diethylaminophenyl)-2-sulfophenyl methane (hereinafter abbreviated as BSPM) (Japanese Patent Application Laid-Open No. 26199/1981). However, it can not necessarily be said that the solubility thereof to water is sufficient.